As-Sunnah by Imaam al-Khallal (311H)

Checked 2 volumes edition (1000 pages).

Checked 3 volumes edition, by 'Atiyah ibn 'Atiq az-Zahrani (1316 pages).

Insha Allah the best edition to date, with the picky Tahqiq of 'Adil Al Hamdan, who has gathered the available manuscripts and corrected all the faults present in previous editions. In addition, there are additional beneficial annotations.
He has also collected all the texts that are attributed to al-Khallal but no longer appear in the manuscripts (quoted by Ibn Battah or adh-Dhahabi, for example).
He added the book ar-Rad 'ala al-Jahmiya of Imam Ahmad, as it is reported by al-Khallal.
Finally there is Juz min Kitab as-Sunnah of Ghulam al-Khallal, a great pupil of al-Khalal who reported from him.